1. Field of the Invention
The present invention relates to an integrated circuit, and more particularly to an integrated circuit for driving high-voltage LED lamp.
2. Description of Prior Art
At present, the LEDs (light-emitting diodes) are widely used, such as LED lamps. However, the prior arts of LED lamp drivers generally have a drawback that the driving circuit can not be integrated into one single semiconductor chip.
The following patents: US 2006/0038542 A1, US 2008/0129220 A1, US 2003/0122502 A1, U.S. Pat. Nos. 6,798,152 B2, 7,135,825 B2, 7,489,086 B2, 7,528,551 B2 , 7,592,755 B2, 6,441,558 B1, 7,288,900 B2, US 2002/0140379 A1, and U.S. Pat. No. 7,642,725 B2 disclosed the lighting applications of the LEDs. All of the above-mentioned lighting applications use at least one of the following devices: transformer, DC power supply, large inductor, large capacitor, and light sensor. Thus, it is impossible to integrate all the bulky devices into one semiconductor chip by using the existing semiconductor processes.
WO 2007/001116 A1 disclosed high-voltage switches with different potentials. In the existing semiconductor manufacturing processes for high voltage resistance, however, there are not suitable components for using. Accordingly, if the integration can not be realized, the production costs can not be effectively reduced. In addition, the current is instantaneously opened or shorted due to the open-circuit voltage switching, this will result in higher EMI. Furthermore, the conduction current is fixed and the total harmonic distortion (THD) is larger than 42%. The existing lighting regulation that the THD has to be smaller than 33% can not be satisfied.
U.S. Pat. No. 6,989,807 disclosed the detection of the voltage level of the input power to turn on and turn off the current-driving circuits in order. However, the temperature variation is neglected due to the forward voltage. This will easily result in higher voltage across the current-driving circuits to reduce the use efficiency. In addition, the optimal switching time can not be controlled and it causes the EMI and the harmonic distortion. Furthermore, the driving current is fixed and the THD is larger than 42%. The existing lighting regulation demanding THD to be smaller than 33% can not be satisfied, even though the power factor is larger than 90%.